GAS-PERMEABILITY OF POLYETHYLENE POLY(ETHYLENE PROPYLENE) SEMICRYSTALLINE DIBLOCK COPOLYMERS

Gas permeability coefficients for several gases (He, CO2, CH4, O2 and N2) were measured at 25-degrees-C in a series of semicrystalline diblo ck copolymers of polyethylene/poly(ethylene-propylene). A simple model is presented describing the gas transport in these polymer systems. I t predicts the permeability of a randomly oriented spherulitic diblock specimen from the values of the permeability coefficients of the indi vidual lamellar regions of the copolymer. Model predictions were in ex cellent agreement with the experimental data. The upper bound (lamella e aligned in parallel with respect to the permeation direction) and lo wer bound (series lamellar alignment) models were calculated and compa red to a limited amount of corresponding experimental data on oriented specimens.